Generally, terminals can be classified as mobile/portable terminals and stationary terminals according to their mobility. The mobile terminals can be further classified as handheld terminals and vehicle mount terminals according to possibility of user's direct portability.
The mobile terminals have become increasingly more functional. Examples of such functions include data and voice communication, image and video capturing through a camera, voice recording, music file playback through a speaker system, and image and video displaying through a display unit. Some mobile terminals include additional functions for supporting game playing and working as multimedia players. In particular, current mobile terminals can receive multicast signals including visual contents such as videos and television programs. Basically, the mobile terminal is connected to the network or other devices through various communication protocols to perform the above-described functions, and thus a ubiquitous computing environment can be provided to users. That is, the mobile terminal has been evolved as a smart device capable of providing connectivity to the network and ubiquitous computing.
Traditionally, such a smart device operating as the mobile terminal has been designed to have a size that allows a user to grab the smart device with a user's hand and thus, the user could carry around the smart device in the hand or put the smart device in a bag or pocket. In accordance with the recent development of technology, the size of the smart device has been remarkably reduced, and thus the smart device has been developed as a wearable smart device, which can be directly worn on a user's body. In particular, efforts have been made to develop and popularize a smart watch worn on a user's wrist, which is one among such wearable smart devices.
The smart watch with a size small enough to be worn on the wrist has been developed to provide not only the typical function of the watch, for example, provision of time information, but also a variety of enhanced functions of the mobile terminal. Further, in the case of a recently developed smart watch, all the above-described functions of the mobile terminal are included therein so that the mobile terminal can be replaced with the recently developed smart watch. For example, similar to the mobile terminal, the smart watch can store various personal information of the user or access the personal information stored in other devices through the network. However, the smart watch has no means of controlling access to the user's personal information, and thus, a security device for protecting the user's personal information should be developed for the smart watch. In addition, a method for protecting the personal information based on such a security device is also required.